The purpose of this proposal is to continue our studies on the specificity of interaction of salivary glycoproteins with oral Streptococci. Glycoproteins which will be studied include mucin, lactoferrin, and secretory IgA. Streptococci to be studied include representative strains of the three seroytpes of Streptococcus sanguis as described in Rosan, 1974. Studies will be aimed at determining what portion of each salivary glycoprotein (ligand) is responsible for interactions with the representative strains of S. sanguis. The specific salivary ligand will then be utilized to isolate the bacterial surface receptor involved in this interaction. Isolation will be performed using affinity chromatography techniques. Purified surface receptors will then be characterized with respect to their chemical composition and physical properties.